Several dozen natural hybrids occur near a 34-year-old plantation of Austrian pine situated near a plantation of Japanese red pine at the W. K. Kellogg Forest in southern Michigan. The oldest hybrid was 26 feet tall at age 18 and had some 3-foot internodes. The hybrids were intermediate in leaf and cone characters. From 1962 to 1964, a total of 2,169 open-pollinated cones was collected from the Austrian pines. The average yield was 26 sound seeds per cone. The seedlings were grown in comparison with pure Austrian and pure Japanese red pines. At age 4, 92 percent were identified as hybrid on the basis of rapid growth, presence of 3-needled fascicles, shorter and less stiff needles than in the female parent, and presence of female flowers. Pines are polyembryonic, and it is likely that the high incidence of hybrids is the result of early heterosis and selection favoring hybrid embryos during the course of seed development. The hybrid may find future use for timber production and roadside plantings.

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